ELECTRICAL STANDARDS 183 



twenty years, began its work as a meteorological 

 station in 1868, and a new observatory was erected 

 in 1885. Magnetic observations were initiated in 

 1887 and were continued down to 1913, when lack 

 of funds and other considerations necessitated the 

 closing of the station. In the previous year a resolu- 

 tion was passed to the effect that a detailed magnetic 

 survey of the British Isles, such as Sir Arthur Riicker 

 and Sir Edward Thorpe had executed for the epoch 

 of 1891, should be repeated, and this, with the con- 

 currence of the Royal Society and other bodies, was 

 duly set on foot, the Association contributing to the 

 cost. 



THE SEA-LEVEL 



The work upon the sea-level, to which a small 

 grant was allocated in 1879, consisted of a careful 

 and detailed investigation of the datum level of the 

 Ordnance Survey of Great Britain, ' with a view to 

 its establishment on a surer foundation than hitherto,' 

 together with an elaborate tabulation of other datum- 

 marks for the purpose of comparison. 



ELECTRICAL STANDARDS 



No committee of the Association has carried out 

 work of more far-reaching importance in application 

 than that upon electrical standards. In 1861 a 

 committee was first appointed to consider the 

 subject of standards of electrical resistance, at 

 the suggestion of Thomson (Kelvin). * When 

 the committee was first appointed no coherent 

 system of units for the measurement of electrical 

 resistance, current, electromotive force, quantity, 



